1. Technical Field
This device relates to intraurethral magnetic valves that are used to provide a valving means for individuals suffering from an inability to control their bladder functions by substituting a mechanical magnetic actuated valve to control the flow of urine.
2. Description of Prior Art
Prior art devices of this type have relied on a wide variety of different magnetic valve configurations that attempt to control the fluid flow from the bladder. Examples of same can be defined and divided into two basic designs; 1) ferromagnetic spheres or slugs which seal an aperture by attraction to one or more fixedly located permanent magnets within a valve housing and are drawn away from the aperture by a strong permanent magnet or electromagnetic field induced by a hand held magnet located outside the valve housing, see for example U.S. Pat. Nos. 3,731,670 and 5,004,454.
The second design group is characterized by permanent magnets bonded to nonmagnetic valve checks which are drawn to seal an aperture by attraction to a ferromagnetic element comprising all or part of the aperture or are resiliently held in closed position on the aperture by a spring. These checks are drawn in a straight linear motion away from the apertured valve seat by a hand held magnet outside the valve housing, see for example U.S. Pat. Nos. 3,812,841 and 5,140,999.
In U.S. Pat. No. 3,731,670 a corporeal fluid control using binary magnetic duct valve is disclosed wherein a mounting tube has two spaced magnets with a steel ball valve element therebetween. The ball valve element is selectively attracted to each of the magnets defining an open or closed state depending on which magnet the ball is engaged. The ball is reciprocated within the structure by an external magnetic force.
U.S. Pat. No. 5,004,454 is directed to an auxiliary intraurethral magnetic valve wherein a plastic tube defines the valve body and a valve seat. A valve element of a ferromagnetic material is held in sealing relation against the valve seat by a spring associated therewith. The valve is opened by imposing a magnetic force on the valve element drawing same away from the seat and stretching the spring.
The devices defined by the first set of prior art valves suffer from an intrinsic difficulty in balancing the magnetic force needed for adequate sealing with the need for reasonable operational range of the activation magnet.
Since magnetic forces are highly nonlinear, decreasing very rapidly with distance from the magnetic poles; when a ferromagnetic ball or slug is held against an aperture by a permanent magnet element the respective switching magnet must be either very large or very close to induce the required force. The slug checks that are drawn to the side of the housing encounter high sidewall friction forces which are induced increasingly as the angle between the housing center line and the line of approach of the switching magnet increases.
In U.S. Pat. No. 3,812,841 a urethra magnetic valve structure can be seen in which a valve element is positioned on a movable magnetic core cylinder. The valve element is held in closed position by an attached spring. Inducing a high electromagnetic force from outside the body will move the magnetic core cylinder and valve element attached thereto opening the valve.
In U.S. Pat. No. 3,812,841, the valve check movement is constrained by the housing to a straight line which necessitates that unless the switching magnet approaches with its axis directly aligned on the center line the force will draw the check against the sidewall imparting torque induced friction decreasing the effectiveness and movement of the check within the valve housing.
U.S. Pat. No. 5,140,999 is directed to an implantable valve structure in which the valve element extends well within the bladder for increased lateral operational movement. The valve element has a compression spring engaging same in a closed or checked position. Upon inducement of an outside magnetic force the magnetizeable member on the free end of the valve element within the bladder is displaced to the side moving the respective valve element off its valve seat opening the valve. No accommodation is made for bladder neck movements or changes in bladder inflation which may cause unwanted movements of the free end of the valve element.
The present invention overcomes the drawbacks of small working distance and sidewall friction by utilizing as operating forces the torque induced between the dipoles of the valve element and the switching magnet and the direct magnetic attraction between same. In the preferred embodiment the valve element pivots freely within the confines of the housing to align its magnetic poles with respective poles of the switching magnet used. This results in a large ratio of switching magnet working distance to housing diameter, virtual omnidirectionality for the switching magnet approach and nonpolarity of the switching magnet orientation.
In an alternate form of the invention, the valve element is hinged so that torque induced by the switching magnet and direct magnetic attraction will cause it to rotate in an arc about a pivot point within the housing aligning its magnetic poles with poles of the switching magnet. The same benefits apply to the alternate form of the invention as hereinbefore described with the preferred embodiment.